Re: better page-level checksums

Robert Haas <robertmhaas@gmail.com>

From: Robert Haas <robertmhaas@gmail.com>

To: Peter Geoghegan <pg@bowt.ie>

Cc: Tom Lane <tgl@sss.pgh.pa.us>, Bruce Momjian <bruce@momjian.us>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>

Date: 2022-06-15T02:21:16Z

Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

Rethink method for assigning OIDs to the template0 and postgres DBs.
- 2cb1272445d2 15.0 landed
pg_upgrade: Preserve database OIDs.
- aa01051418f1 15.0 landed
pg_upgrade: Preserve relfilenodes and tablespace OIDs.
- 9a974cbcba00 15.0 landed
Fix for new Boolean node
- cf925936ecc0 15.0 cited
Improve error handling of HMAC computations
- 5513dc6a304d 15.0 cited
Add macro RelationIsPermanent() to report relation permanence
- 95d77149c535 14.0 landed
Enhance nbtree index tuple deletion.
- d168b666823b 14.0 cited

On Tue, Jun 14, 2022 at 9:56 PM Peter Geoghegan <pg@bowt.ie> wrote:
> Technically we don't already do that today, with the 16-bit checksums
> that are stored in PageHeaderData.pd_checksum. But we do something
> equivalent: low-level tools can still infer that checksums must not be
> enabled on the page (really the cluster) indirectly in the event of a
> 0 checksum. A 0 value can reasonably be interpreted as a page from a
> cluster without checksums (barring page corruption). This is basically
> reasonable because our implementation of checksums is guaranteed to
> not generate 0 as a valid checksum value.

I don't think that 'pg_checksums -d' zeroes the checksum values on the
pages in the cluster.

-- 
Robert Haas
EDB: http://www.enterprisedb.com